As one of the best Action/Adventures for the SMS, this game shouldn't be forgotten.
"The Dragon's Trap" is not only the best game of this series, it is also by far one of the best games for the SMS.
In the beginning you actually replay the end of Wonder Boy II: You find your way through a castle until you confront the "Mecha-Dragon". After beating him he curses and transforms you into a lizard-like-being. This event actually gives the game its name.
Your goal from now on is, of course, to transform yourself back into the human being you once were.
To regain your human form you have to beat some mean dragons. Now here comes the part which gives Wonder Boy III it's interesting gameplay: After killing one of those dragons you gain a new form. Throughout the game you transform from lizard, to mouse, to piranha-, lion- and hawk-man. Each of those have unique abilities. For example, as a mouse you can walk on walls or as a hawk-man you can (surprise.....) fly. From a certain point on you get the option to change between those forms whenever you like, which let's you visit old regions to find new stuff.
While you explore the castles and the surrounding lands, you hit your enemies (snakes, skeletons and those kind of foes) mainly with your sword and some special-attacks (like a little fireball, a tornado or a thunder that hits every enemy on the screen).
You energy consists of hearts. You can find new hearts to increase your life (sounds familiar, doesn't it).
You also find different types of swords, shields and armors in shops. There is only one town in the whole game where you can buy stuff (though there a some other shops spread throughout the different regions), let your wounds be cured or find the current password.
The graphics were some of the best for that time. They just have this certain charm with them. The movement in this 2-D side-scrolling adventure just feels good.
The music and the soundeffects are also very good, nothing to complain here.
Now, the saving system is one of the weak points of the game: Like most games of that time you have to write down a long password that you need to "load" your game.
Another thing that can be annoying at times is that the difficulty isn't very well balanced. Sometimes it's very easy, then all of a sudden it becomes much harder.
One last point of negative critic is that the game is a little short. But in the few hours you spend with this game you can have a lot of fun.
"Wonder Boy III: The Dragon's Trap" is a very good game which shows that even such old games can still be a lot of fun today.